(a) Field of the invention
The present invention relates to a zoom lens system which is small, light in weight and has sufficient wide-angle effect as well as zooming effect.
(b) Description of the prior art
There has conventionally been known zoom lens systems having a simple composition consisting of a front lens group and a rear lens group, for example, those disclosed by Japanese Published Unexamined Patent Application No. 83543/76 and Japanese Published Unexamined Patent Application No. 60246/78. Out of these zoom lens systems, the former is designed for an aperture ratio of F/2.8 and a zooming ratio of 1.9 which assure sufficient brightness and zooming effect but cannot provide sufficient wide-angle effect due to a field angle of 2.omega.=64.6.degree. at the wide angle position. The latter is designed for an aperture ratio of F/3.5, a zooming ratio of 1.67 to 1.85 and a field angle 2.omega.=52.degree. to 54.degree., but cannot provide sufficient wide-angle effect either.